Effects of some biological properties of the stripped bug, Graphosoma lineatum (L.) (Hem., Scutelleridae) on its salivary alpha-amylase activity

Types of insects digestive enzymes are generally associated with their food regimes; and at least, the predominant presence of an enzyme indicates that the diets of the target insects contain high levels of its substrate. Insect digestive enzymes show considerable different activities in relation to their individual conditions and developmental stages. In this study, it was revealed that the type of food (several kinds of seeds of umbelliferous plants) had no significant effects on the enzyme activity of the stripped bug, Graphosoma lineatum (L.). The results showed that the enzyme activity in male and female adults will differ 4.5 and 3.5 times, respectively, if the insects’ biological and physiological conditions are not similar. In general, females’ enzyme activity was greater than that of the males. Environmental temperatures (4-30 ˚C) did not affect the α-amylase activity. In starved insects (0-48 hours), the most enzyme activities were observed in 24-hour (12.32 U/mg protein) and 36-hour (14.13 U/mg protein) starved insects which had not significant difference to each other. Enzyme activities were similar between the two salivary glands of an individual bug which shows that these two glands respond to the related stimuli simultaneously. During the circadian cycle, enzyme activities were different. This was related to the different conditions of the used insects. α-amylase activities in insects obtained from 10th to 17th generations had not significant differences to each other. Despite from the similarities between some results of the present study with the results of other researchers, we confirm this theory that we are not able to establish a generalization about insect digestive enzymes properties and each species should be investigated separately.